1. Field of the Invention
The present invention relates generally to the field of computer-implemented inventions, and more specifically, to a computer-implemented method for identifying reconstructive prosthetic devices that have been implanted in patients.
2. Description of the Related Art
A need exists within the orthopedic community for a method that will assist orthopedic surgeons and their allied health professionals in the identification of existing total hip, total knee, and total shoulder implants within their patient population. Approximately 2,201,000 primary Total Hip Arthroplasty (THA) procedures and 3,870,000 primary Total Knee Arthroplasty (TKA) procedures were performed in the 14-year period from 1991 through 2004 [1]. During this same time period, it was estimated that 453,000 revision THA procedures and 340,000 revision TKA procedures were completed. Of the cumulative THA procedures, 21% were revisions. Of the cumulative TKA procedures, 8.8% were revisions. A more detailed study completed by Kurtz et al. [2] utilizing this same data calculated the “Revision Burden” for revision THA and TKA procedures to be 17.5% and 8.2%, respectively.
Across the United States, primary THA and TKA patients are walking—or limping—into orthopedic practices because of pain or dysfunction associated with their initial replacements. As the orthopedist reviews the patient's x-rays, MRI, CT-scan, bone scan and patient history, he often finds loose implants, worn polyethylene components, osteolysis (bone loss or bone destruction) and/or malpositioned implants, each of which requires varying degrees of revision surgery. Identification of the implant prior to surgery decreases both patient risk and cost, but this information is not always readily available. For example, the primary procedure may have been performed in Miami, Fla. in 1995 by a surgeon that retired in 1999, and the patient has since relocated to Phoenix. In this situation, the patient's operative record is not easily obtained. Office staff need to make numerous phone calls to the physician's office, the hospital where the surgery was completed, and the patient in order to get some record of which implant was used. Records may exist, but they are on microfiche in storage, and the person answering the phone often has no financial incentive to help.
The reason identification of the initial implant is so important is because there are numerous orthopedic implant manufacturers within the United States and abroad, each with an array of differing implants, and standardization does not exist within the industry. Nearly every implant boasts certain unique design characteristics that purport to make it better than competitive products. If the implant is identified, the necessary implant manufacturer's representative can be contacted and notified of the scheduled surgery, and adequate revision implant components and instruments can then be made available for the surgeon and patient on the day of the surgery. If the implant cannot be identified with certainty, the surgeon will approach the operating room with plans to extract all existing hardware and completely replace all components with new implants. The latter approach poses greater risk of blood loss and fracture, longer anesthesia exposure, and post-operative complications including deep vein thrombosis and pulmonary embolism. In addition to these health risks, this “blind” approach entails excess costs associated with a complete removal of what may be perfectly acceptable components and their replacement with more costly revision components. The actual number of “blind” revision arthroplasties completed annually is unknown but is believed to be substantial.
The most comprehensive resource tool currently available to orthopedists is the Orthopaedic Device Reference compiled by the Association of Bone and Joint Surgeons in 1998 [3]. This 253-page guide references implants for total hips, total knees, total shoulders, total elbows, total wrists, total ankles, implantable trauma devices, non-implantable trauma devices. For total hips and total knees, only seven manufacturers are referenced: Biomet, DePuy, Howmedica, Implex, Johnson & Johnson, Smith & Nephew, Zimmer. Since 1998, many of these companies have merged. In addition, many U.S. and European manufacturers were completely omitted from the publication. Each implant has a representative photograph, but no patient x-rays are included in the guide for visualization of the prosthesis once implanted. Furthermore, the reference is in book format, which requires manually leafing through hundreds of pages of implants to find the right one. This reference book is not a practical nor efficient solution to the problem of identifying an existing implant.
As the number of THA and TKA arthroplasties continues to rise annually, the quantity of revision procedures will also continue to rise. The Kurtz study [2] predicts that in 2020, 384,324 primary THAs, 67,607 revision THAs, 1,520,348 primary TKAs and 120,928 revision TKAs will be performed annually. These numbers represent a 70% increase over 2007 projected figures for total (primary and revision) THAs and a nearly 200% increase over 2007 projected figures for total (primary and revision) TKAs [2]. These numbers suggest that the need for a method of accurately identifying implants in patients will only increase.
According to a report by Ong et al. [4], revision THA charges are projected to increase from $0.97 billion to $3.81 billion between 2005 and 2015. Revision TKA charges are projected to increase from $0.75 billion to $4.12 billion [5]. These cost increases may be dramatically reduced if surgeons are able to identify the implants in patients prior to the surgery.
For these reasons, what is needed is a comprehensive orthopedic implant database and software application that will allow orthopedists to accurately identify existing implants utilizing patients' radiographic images. Accordingly, it is an object of the present invention to provide a computer-implemented method that accepts radiographic images of prosthetic devices implanted in patients as inputs and identifies them according to a database of known implantable prosthetic devices in order to assist physicians preparing for device repair or replacement surgery.